SELF-INDUCED, PHOTOCHEMICAL, SINGLET-OXYGEN OXIDATION OF 4-NITROBENZENESULFENATES TO 4-NITROBENZENESULFINATES

It has been previously reported that the photo-induced homolytic dissociation of homoallyl an 4-nitrobenzenesulfenates, followed by beta-scission of the alkoxy radicals to allyl and alkyl radicals leads to the formation of sulfides. In the presence of dioxygen the alkyl sulfenates undergo oxidation to the corresponding alkyl sulfinates. The results of theoretical studies suggest that the absorption of the photon results in the excitation of an electron from the pi-type sulfur nonbonded-pair MO (the HOMO) to a pi* MO of the aromatic ring (the LUMO). Quenching studies indicate that a triplet excited state is ultimately formed which then reacts with triplet dioxygen to form singlet dioxygen, which can be trapped with 1,3-cyclohexadiene, which then reacts with ground-state sulfenate.